For the layer-wise construction of three-dimensional objects from “lighthardening” materials, various processes are mentioned in literature, see in this respect “Automated Fabrication-Improving Productivity in Manufacturing” of Marshall Burns, 1993 (ISBN 0-13-119462-3).
This invention relates to processes wherein the layer to be generated is based on illumination by means of a rastered mask, wherein the smallest physical resolution within the mask is provided by the size of a pixel.
Known possibilities presently are, inter alia, illumination by                a) Projection unit (on the basis of DLP®/DMD®, LCD, ILA®, etc.)        b) LD-display (reflective, transmissive)        c) LED-, or laser-diode-line/-matrix (which is moved in XY-plane over the layer)        d) Line or matrix (which is moved in XY-plane over the layer) based on MEM-technology (light-valve).        
Some of these methods are described in the following patents:
IPC: B29C67/00 “Rapid Prototyping apparatus and method of Rapid Prototyping” of Dicon AS (DK), (application)
U.S. Pat. No. 5,247,180 A “Stereolithographic Apparatus and Method of use” of Texas Instruments Inc., September 1993.
U.S. Pat. No. 5,980,813 A “Rapid Prototyping using multiple materials” of SRI International, November, 1999;
Utility Model DE G 93 19 405.6 “Device for the production of a three-dimensional object (model) according to the principle of photosolidification” of Research Center Informatik at the University Karlsruhe, Dez. 1993;
An application for the generation of micro-technical, three-dimensional construction parts according to a similar process is described in the Utility Model DE 299 11 122 U1 “Device for the production of a three-dimensional object” DeltaMed et al., June 1999.
PCT Application 02 008 019.8 “Device for the production of a three-dimensional object” of Envision Technologies GmbH, April 2002.
U.S. Pat. No. 6,180,050 describes a linear scan technique for layer-wise solidification in the production of three-dimensional objects. The resolution is enhanced by scanning, in X-direction, an illumination head having an array of optical fibers, which are displaced in the Y-direction.